1. Field of the Invention
The present invention relates to the field of optical elements that are polarized, and more particularly to a controlled rotating linearly polarized optical element used on a digital camera or Smartphone or any device or means capable of acquiring and, in most cases, processing digital images. The object of the invention is to create enhanced views of scenes that maximize the appearance of the net polarization of light that is reflected or scattered to an observer from the various elements within the scene, or to render the net polarization in the scene amenable to automatic detection of features of interest within the image.
2. Description of Related Art
As can be seen by reference to the following U.S. Pat. Nos. 8,449,409; 7,713,148; 5,414,476; and JP2004317124A2; JP10148521A2; and WO2009128340A1, the prior art is replete with myriad devices designed to enhance certain characteristics of scenes, making them far more apparent to the user.
Normal visible light has a component, referred to as the electric vector that is usually oriented in a random direction that is perpendicular to the path of the light beam. Polarized material allows only that light that has its electric vector oriented parallel to a preferential direction to pass through the material. This is analogous to a rope in a picket fence. Without the fence one can create wave motion in the rope horizontally, vertically or any angle in between, representative of the randomness of the wave states. But, if the rope goes through the fence, all horizontal motion is damped by the presence of the fence while the vertical is not.
Light that does not have its electric vector more or less parallel to that direction will be absorbed. Light that passes through such a polarized filter has all its electric vectors aligned in one direction, and is said to be polarized. The fraction of light that is absorbed is proportional to the cosine of the angle between the electric vector of the light and the preferential direction. As in conventional polarized sunglasses, each polarized lens has a preferential direction for light filtering. In conventional fixed-mount polarized sunglasses, the polarized preferential direction is vertical for both eyes. This allows light that has its electric vector oriented vertically to pass through unattenuated, light that has been reflected from horizontal surfaces, e.g., a car hood, or the road surface or the water's surface tends to have its electric vector oriented horizontally, and is thus preferentially absorbed by the polarized lens. This is the reason that conventional polarized sunglasses are so efficient at reducing reflected glare.
Many other situations result in different net polarizations of light reflected from various surfaces. Polarization differences in a scene are indicative of differences in the reflecting or scattering surfaces, differences that are not apparent without somehow enhancing the small differences in polarization, to which the eye is not sensitive. These differences include, for instance, light reflected from a golfing green, with different polarizations indicative of different types of grass, or subtle undulations in the green itself. We shall use golf and golfers as examples throughout this application, though it is understood that the principles are universally applicable.
To reiterate, the important point is that humans and the unaided human eye are not sensitive in any way to the net polarization of a scene; having an eye that is sensitive to net polarization would be analogous to the difference between seeing in black and white and seeing in color.
While all of the aforementioned prior art constructions are adequate for the basic purpose and function for which they have been specifically designed, they are uniformly deficient with respect to their failure to provide a simple, efficient, and practical optical element that maximizes and displays the polarization differences that are inherent in any particular scene. In its simplest form, our approach posits a motorized rotating optical polarizing element for use on a digital camera or a Smartphone.
By “motorized” we mean any remotely or automatically controlled or programmed device that changes the preferential filtering direction of a linearly polarizing optical element. The term “linearly polarizing optical element” applies to both the familiar physical forms of polarizer, e.g., the common plastic Polaroid filters, as well as to electronic devices, e.g., those based on Pockels cells, for instance. By “camera” we mean any device or system that is capable of acquiring an image and storing it digitally. Cameras usually have an optical lens, but the term “camera” can include any image formation device, e.g., a telescope minor. The term “microprocessor” means any computing device having a memory capability and computer code that receives digital image input and can output data generated by the computer code. If a capital letter such as P(i) is used to represent digital image number i in a sequence of digital images, then P(i, m, n) represents the individual pixel of P(i) in row m column n.
This new and improved motorized rotating linearly polarized optical element and its ability to present maximum net polarization, or any function of net polarization, inherent in any scene is a stated object of the present invention.